[pushed] gdb/18216: displaced step+deliver signal, a thread needs step-over, crash

[Pedro Alves]

The problem is that with hardware step targets and displaced stepping,
"signal FOO" when stopped at a breakpoint steps the breakpoint
instruction at the same time it delivers a signal.  This results in
tp->stepped_breakpoint set, but no step-resume breakpoint set.  When
the next stop event arrives, GDB crashes.  Irrespective of whether we
should do something more/different to step past the breakpoint in this
scenario (e.g., PR 18225), it's just wrong to assume there'll be a
step-resume breakpoint set (and was not the original intention).

gdb/ChangeLog:
2015-04-10  Pedro Alves  <palves@redhat.com>

	PR gdb/18216
	* infrun.c (process_event_stop_test): Don't assume a step-resume
	is set if tp->stepped_breakpoint is true.

gdb/testsuite/ChangeLog:
2015-04-10  Pedro Alves  <palves@redhat.com>

	PR gdb/18216
	* gdb.threads/multiple-step-overs.exp: Remove expected eof.
---
 gdb/ChangeLog                                     | 6 ++++++
 gdb/testsuite/ChangeLog                           | 5 +++++
 gdb/infrun.c                                      | 3 ++-
 gdb/testsuite/gdb.threads/multiple-step-overs.exp | 7 -------
 4 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index be8eabb..83f9df6 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2015-04-10  Pedro Alves  <palves@redhat.com>
+
+	PR gdb/18216
+	* infrun.c (process_event_stop_test): Don't assume a step-resume
+	is set if tp->stepped_breakpoint is true.
+
 2015-04-10  Yao Qi  <yao.qi@linaro.org>
 
 	* arm-tdep.c (install_alu_reg): Update comment.
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 2d19d45..c47c6ac 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2015-04-10  Pedro Alves  <palves@redhat.com>
+
+	PR gdb/18216
+	* gdb.threads/multiple-step-overs.exp: Remove expected eof.
+
 2015-04-10  Yao Qi  <yao.qi@linaro.org>
 
 	* gdb.arch/arm-disp-step.S (main): Call test_add_rn_pc.
diff --git a/gdb/infrun.c b/gdb/infrun.c
index d52b8ad..3fcc55f 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -4961,7 +4961,8 @@ process_event_stop_test (struct execution_control_state *ecs)
       struct breakpoint *sr_bp
 	= ecs->event_thread->control.step_resume_breakpoint;
 
-      if (sr_bp->loc->permanent
+      if (sr_bp != NULL
+	  && sr_bp->loc->permanent
 	  && sr_bp->type == bp_hp_step_resume
 	  && sr_bp->loc->address == ecs->event_thread->prev_pc)
 	{
diff --git a/gdb/testsuite/gdb.threads/multiple-step-overs.exp b/gdb/testsuite/gdb.threads/multiple-step-overs.exp
index bfa4ad1..475e0f4 100644
--- a/gdb/testsuite/gdb.threads/multiple-step-overs.exp
+++ b/gdb/testsuite/gdb.threads/multiple-step-overs.exp
@@ -118,13 +118,6 @@ foreach displaced { "off" "on" } {
 			}
 			fail $msg
 		    }
-		    eof {
-			if {[can_single_step_to_signal_handler]
-			    && $displaced == "on"} {
-			    setup_kfail "gdb/18216" "*-*-*"
-			}
-			fail $msg
-		    }
 		}
 	    }
 	}
-- 
1.9.3